H-Ras nanocluster stability regulates the magnitude of MAPK signal output.

• Main Authors: Barak Rotblat, Liron Belanis, Hong Liang, Roni Haklai, Galit Elad-Zefadia, John F Hancock, Yoel Kloog, Sarah J Plowman
• Format: Article
• Language: English
• Published: Public Library of Science (PLoS) 2010-08-01
• Series: PLoS ONE
• Online Access: http://europepmc.org/articles/PMC2916832?pdf=render

H-Ras is a binary switch that is activated by multiple co-factors and triggers several key cellular pathways one of which is MAPK. The specificity and magnitude of downstream activation is achieved by the spatio-temporal organization of the active H-Ras in the plasma membrane. Upon activation, the GTP bound H-Ras binds to Galectin-1 (Gal-1) and becomes transiently immobilized in short-lived nanoclusters on the plasma membrane from which the signal is propagated to Raf. In the current study we show that stabilizing the H-Ras-Gal-1 interaction, using bimolecular fluorescence complementation (BiFC), leads to prolonged immobilization of H-Ras.GTP in the plasma membrane which was measured by fluorescence recovery after photobleaching (FRAP), and increased signal out-put to the MAPK module. EM measurements of Raf recruitment to the H-Ras.GTP nanoclusters demonstrated that the enhanced signaling observed in the BiFC stabilized H-Ras.GTP nanocluster was attributed to increased H-Ras immobilization rather than to an increase in Raf recruitment. Taken together these data demonstrate that the magnitude of the signal output from a GTP-bound H-Ras nanocluster is proportional to its stability.